Food tin with vacuum sealed lid

ABSTRACT

A can comprises a metal can body and a metal lid. The can body has an edge defining a top opening into the body, and an inwardly directed bead (22) extending around the body adjacent to the top opening. The bead defines an upwardly facing sealing surface (25) and an inwardly facing surface (26). The lid has a centre panel (30), a wall (32) surrounding the centre panel, and an outwardly directed curl (34) at the top of the wall. The curl defines a peripherally extending channel (35) having an opening therein, and sealing compound (36) is located within the channel and projects through the opening. The can body and the lid are dimensioned to allow the lid to be press-fitted into the can body, so that an outwardly facing surface of the wall opposes the inwardly facing sealing surface of the bead, whilst the sealing compound is in sealing engagement with the upwardly facing sealing surface of the bead.

TECHNICAL FIELD

The present invention relates to metal food cans with reclosable lids. More particularly the invention relates to metal food cans suitable for containing food products and which, once filled, provide a vacuum seal between the can body and the can lid.

BACKGROUND

It is common for food stuffs to be packaged within metal cans having metal lids that are press-fitted into the openings in the can bodies. The lids can be prised-off of the can bodies using, for example, the end of a spoon. Such cans are often used with dried food products such as cocoa powder or relatively viscous products such as treacle and syrup. As the seal between the can body and the lid is formed between opposed metal surfaces however, and is generally not air tight at least following opening and reclosing, such cans are generally not used for products that either degrade when in contact with the air or which otherwise require a higher standard of hygiene, such as is the case with infant formula.

For perishable products such as infant formula, assuming that a metal can body is used, a closure system is often used that has a peelable foil lid sealed to the upper surface of a bead pressed into the can body adjacent to the opening. Once the lid is peeled off it is of course not possible to tightly reclose the can with that foil lid. To facilitate reclosure a plastic overcap is typically provided and which is press-fitted over the can body opening above the foil lid. The plastic overcap also provides protection for the relatively weak foil lid during transit and storage. As it is desirable to allow customers to see the foil and verify its integrity prior to purchase, the plastic overcap is often fully or at least partially transparent.

Producers and consumers are keen to reduce the use of plastics and therefore plastics waste. There is therefore a desire to produce an all metal food can which provides a seal between the can body and the lid that is of sufficient integrity to provide for the long term storage of perishable food stuffs whilst allowing for reclosing.

SUMMARY

Embodiments of the present invention provide a metal food can that provides an air and liquid tight seal combined with a means for allowing consumers to verify the integrity of the seal prior to first opening, whilst avoiding the need for a plastics overcap.

According to a first aspect of the present invention there is provided a can comprising a metal can body having an edge defining a top opening into the body, the body further comprising an inwardly directed bead extending around the body adjacent to said top opening, the bead defining an upwardly facing sealing surface and an inwardly facing surface. The can further comprises a metal lid having a centre panel, a wall surrounding said centre panel, an outwardly directed curl at the top of said wall, the curl defining a peripherally extending channel having an opening therein, and sealing compound located within said channel and projecting through said opening. The can body and the lid are dimensioned to allow the lid to be press-fitted into the can body so that an outwardly facing surface of said wall opposes the inwardly facing sealing surface of said bead, whilst said sealing compound is in sealing engagement with said upwardly facing sealing surface of the bead.

The can body may be a single piece can body and said inwardly directed bead is pressed into the can body.

The can body may comprise an annular can end component fixed to a can body wall, said component defining the inwardly directed bead.

The can may further comprise an end closing a bottom of said can body, the lid being engaged with the can body and the can body containing a product, a partial vacuum being present within the can in order to pull the lid onto the can body, thereby compressing said sealing compound between the lid and the can body and effecting a substantially air tight seal between the lid and the can body.

The centre panel may define a pop-up button within a central region thereof, such that the button is depressed when the lid is engaged with the can body and a partial vacuum is present within the can and is in a raised position when the partial vacuum is released.

The can body and the lid may be dimensioned to provide a gap of at least 1 mm between an outermost edge of said curl and an inner surface of said top opening.

A gap between the upwardly facing sealing surface of the bead and a top of the edge may be approximately 3 mm.

The can body may comprise a sheet of metal rolled into a cylinder with a welded seam joining the opposed edges of the sheet.

The can body may comprise a base secured to the can body to close a bottom opening of the can body.

The edge of the can body may be a curled edge.

The radially outermost region of the inwardly directed bead may be collapsed in an axial direction to substantially close the bead to an area surrounding the can body.

The inwardly directed bead may have a substantially oval axial cross-sectional shape.

The upwardly facing sealing surface and the inwardly facing surface defined by the bead may be substantially convex.

The outwardly facing surface of the lid wall may be substantially flat.

The can body and the lid may be dimensioned such that, when the lid is press-fitted into the opening of the can body, an upper surface of the lid is below the top of the can body.

When the lid is engaged with the can body, the outwardly facing surface of the wall may abut the inwardly facing sealing surface of the bead, providing a metal to metal seal.

When the lid is engaged with the can body, the sealing compound may extend over the outwardly facing surface of the wall to seal said outwardly facing surface to the inwardly facing sealing surface of the bead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a can according to the present invention;

FIG. 2 a is a close-up view of the can of FIG. 1 , illustrating a can lid;

FIGS. 2 b and 2 c are cross-sectional views of the lid of FIG. 2 a showing a pop-up button;

FIG. 3 is a cross-sectional view of a portion of the can of FIG. 1 ; and

FIG. 4 is a perspective view of the can of FIG. 1 , illustrating removal of the lid.

DETAILED DESCRIPTION

FIGS. 1 to 4 illustrate a can 10 (for example, a food can or “tin”) comprising a metal can body 20 and a metal lid 30. The can body 20 has an upper curled edge 21, or rim, defining a top opening into the body 20, and comprises an inwardly directed bead 22 extending circumferentially around the body 20 adjacent to the top opening.

The top of the bead 22 is spaced approximately 3 mm from the top of the edge 21. As is pointed out in FIG. 3 , the inwardly directed bead 22 defines a substantially upwardly facing sealing surface 25 and an inwardly facing sealing surface 26. The metal lid 30 has a centre panel 31, a wall 32 surrounding the centre panel 31 and an outwardly directed curl 34 at the top of the wall 32. The curl 34 defines a circumferentially extending channel 35 having an opening 37 therein. Sealing compound such as plastisol 36 is located within the channel 35 and projects through the opening 37.

The inwardly directed bead 22 may be pressed into the body 20, such that the body 20, including the bead 22, is formed from a single, homogeneous piece of metal, as best illustrated in FIG. 3 . Alternatively, a separate annular can end component (i.e. a ring) may be attached to the can body to enable the lid to be replaceably secured to the top opening of the can body. For example, the ring may be non-removably seamed around the top opening of the can body. The ring may be made by stamping out a blank from a flat sheet and subsequently forming the blank to have an appropriate cross-sectional shape, defining an annular space or gap between the inner and outer edges of the ring. The ring may be further formed at its innermost region to provide a substantially circular, upwardly facing sealing surface and an inwardly facing sealing surface.

The can body 20 and the lid 30 are dimensioned to allow the lid 30 to be press-fitted into the can body 20, so that an outwardly facing surface 38 of the lid wall 32 abuts the inwardly facing sealing surface 26 of the bead 22, and the sealing compound 36 is in sealing engagement with the upwardly facing sealing surface 25 of the bead 22.

As best illustrated in FIG. 1 , the can body 20 comprises a base 40 secured to the can body 20 to close a bottom opening of the can body 20. The base 40 may, for example, be secured to the can body 20 by seaming. The can body 20 is generally cylindrical in shape, and is formed from a sheet of metal rolled into a cylinder. Opposed edges of the metal sheet are joined together via a welded seam (not shown here). The can body 20, lid 30 and base 40 may be formed from steel, tinplate, aluminium, or other suitable metal or metal alloy. Preferably, a single material is used for all three elements of the can 10 such that the can 10 is more easily recyclable.

FIG. 2 a illustrates the can lid 30 in more detail. The centre panel 31 of the lid 30 defines a circular, bi-stable pop-up button 33 within a central region thereof. As shown in Figures and 2 c 2 b, the button 33 may comprise an outer, inclined wall 33 a circumferentially surrounding a substantially flat panel 33 b, in the centre of which is an inner circular region 33 c. The inner circular region 33 c is configured to be moveable between a position in which it is slightly raised above the flat panel 33 b (as shown in FIG. 2 b ), and a position in which it is substantially level with the flat panel 33 b (FIG. 2 c ). The button 33 may have a height above the centre panel 31 of approximately 1 mm when in a raised position, as shown in FIG. 2 a . In one non-limiting example, where the centre panel 31 has a diameter of approximately 75 mm, the button 33 may have a diameter of approximately 34 mm.

When the lid 30 is engaged (i.e. press-fitted) with the can body 20, and a partial vacuum is present within the filled can 10, the pop-up button 33 is depressed, as shown in FIG. 2 c.

In this depressed position, an upper surface of the pop-up button 33 (i.e. the flat panel 33 b and the inner circular region 33 c) may be substantially level with the centre panel 31. When the partial vacuum is released from the can body 20 during removal of the lid 30 or as a result of a leak caused by a failure in the can, the pop-up button 33 moves to a raised position (FIG. 2 b ). In the raised position, an upper surface of the pop-up button 33, comprising at least the inner circular region 33 c, is above a level of the centre panel 31 but is easily depressed by a user. The pop-up button 33 thereby provides a tactile and visual indication that the partial vacuum has been released (i.e. tamper evidence).

As illustrated in FIG. 3 , when a partial vacuum is present within the can 10, the can lid 30 is pulled onto the can body 20. This acts to compress the sealing compound 36 that is positioned between the lid 30 and the can body 20, providing a substantially air tight seal between the lid 30 and the can body 20. The sealing compound 36 is preferably foamed to improve compressibility and provide an effective vacuum seal between container body 20 and lid 30.

In this example, once press-fitted onto the can body 20, the top of the lid curl 34 is below the curled edge 21 (i.e. the rim) that defines the top opening of the can body 20. This arrangement may assist in protecting the vacuum seal, e.g. preventing accidental knocking of the lid during transport.

FIG. 3 also illustrates the engagement of the lid 30 with the can body 20. The sealing compound 36 is located partially within the channel 35 defined by the outwardly directed curl 34 in which the lid wall 32 terminates. The curl 34 is open to the extent that the channel 35 has an opening 37 substantially facing the bead 22 of the can body 20. In this example, the compound 36 substantially fills the channel 35 and also projects through the channel opening 37, such that it extends down a portion of the lid wall 32. An outer surface of the lid wall 32 forms an outwardly facing sealing surface 38 which engages with the bead 22. The sealing surface 38 formed by the lid wall 32 may be substantially flat. In this example, the lid sealing surface 38 directly contacts the bead 22 to provide a metal-to-metal configuration.

In an alternative arrangement, not shown here, the sealing compound may extend further down the lid wall 32 such that lid sealing surface 38 does not directly contact the bead; instead the compound 36 forms a seal between the lid sealing surface 38 and the bead 22.

As shown in FIG. 3 , the bead 22 may be “crushed”, i.e. the radially outermost region 24 of the bead 22 may be collapsed in an axial direction. This substantially closes the bead 22 to an area surrounding the can body 20, thus preventing dirt and/or other objects from entering the bead's interior. Similarly, the upper end of the can body 20 may terminate in a closed curl 23 which forms the curled edge 21, which prevents ingress of dirt and avoids sharp edges on the can 10. In other embodiments however the bead 22 may be left open to a greater or lesser extent.

In this illustrated example, the bead 22 has a substantially oval axial cross-sectional shape. The bead 22 may be substantially symmetrical about a longitudinal axis A. The upwardly facing sealing surface 25, defined by the bead 22 is substantially convex (i.e. outwardly curved). Similarly, in this example, the inwardly facing sealing surface 26 defined by the bead 22 is substantially convex in shape.

In use, the lid 30 is provided with a layer of sealing compound 36 within the channel 35 and is then press-fitted onto the can body 20. The sealing compound 36 protrudes through the channel opening 37 such that the sealing compound 36 forms a seal against the upwardly facing sealing surface 25 of the can body bead 22, and such that the lid sealing surface 38 engages with the inwardly facing surface 26 of the can body bead 22. As previously discussed, the partial vacuum formed within the can body 20 holds the lid 30 onto the can body 20, such that the sealing compound 36 is compressed against the bead 22. This partial vacuum may be formed during filling, e.g. by steam flushing or vacuum seaming, or may result from a cooling of a hot filled product.

The seal between the layer of sealing compound 36 provided on an underside of the lid rim, and the bead 22 of the metal can body 20, ensures that the partial vacuum within the can body 20 is securely maintained, even where the can is dropped or knocked. In the case of a can body 20 having a longitudinal weld, as described herein, a metal-to-metal seal alone may be insufficient to maintain the vacuum whereas sealing using a compound allows the discontinuity resulting from the weld to be effectively smoothed-out.

Referring back to FIG. 3 , the can body and the lid are dimensioned to provide a gap 27 of at least 1 mm between an outermost edge of the lid curl 34 and an inner surface 28 of the top opening of the can body. Preferably, this gap 27 may be between 2 to 3 mm wide. This gap is sufficient to allow the lid to be removed with a suitable lever. This is illustrated in FIG. 4 where, in order to remove the lid 30 and open the can 10, the end of a spoon 50 is inserted into the gap 27. It will be appreciated that the lid 30 may be subsequently pushed back on to re-close the can body 20. In this case, a seal is re-formed between the compound and the bead (although clearly the vacuum seal cannot be re-formed). This is particularly useful for products which deteriorate on exposure to air.

The above-described can essentially provides a single material packaging solution for products, such as food products which previously may have required the use of a peelable foil lid and an overcap. The use of plastics is therefore avoided apart from a small amount of sealing compound. Further, the metal lid may be beneficially printed or otherwise marked with indicia, or the like. 

1. A can comprising: a metal can body having a body edge defining a top opening into the body, the body further comprising an inwardly directed bead extending around the body adjacent to said top opening, the bead defining an upwardly facing sealing surface and an inwardly facing surface; and a metal lid having a centre panel, a lid wall surrounding said centre panel, an outwardly directed curl at the top of said wall, the curl defining a peripherally extending channel having an opening therein, and sealing compound located within said channel and projecting through said opening, the can body and the lid being dimensioned to allow the lid to be press-fitted into the can body so that an outwardly facing surface of said lid wall opposes the inwardly facing sealing surface of said bead of the can body, whilst said sealing compound is in sealing engagement with said upwardly facing sealing surface of the bead.
 2. A can according to claim 1, wherein the can body is a single piece can body and said inwardly directed bead is pressed into the can body.
 3. A can according to claim 1, the can body further comprises an annular can end component fixed to a can body wall, said component defining the inwardly directed bead.
 4. A can according to claim 1, further comprising an end closing a bottom of said can body, the lid being engaged with the can body and the can body containing a product, a partial vacuum being present within the can in order to pull the lid onto the can body, thereby compressing said sealing compound between the lid and the can body and effecting a substantially air tight seal between the lid and the can body.
 5. A can according to claim 4, wherein said centre panel defines a pop-up button within a central region thereof, such that the button is depressed when the lid is engaged with the can body and a partial vacuum is present within the can and is in a raised position when the partial vacuum is released.
 6. A can according to claim 1, wherein the can body and the lid are dimensioned to provide a gap of at least 1 mm between an outermost edge of said curl and an inner surface of said top opening.
 7. A can according to claim 1, wherein a gap between the upwardly facing sealing surface of the bead and a top of the body edge is approximately 3 mm.
 8. A can according to claim 1, the can body further comprises a sheet of metal rolled into a cylinder with a welded seam joining opposed edges of the sheet.
 9. A can according to claim 4, the can body further comprises a sheet of metal rolled into a cylinder with a welded seam joining opposed edges of the sheet and a base secured to the can body to close a bottom opening of the can body.
 10. A can according to claim 1, wherein said edge of the can body is a curled edge.
 11. A can according to claim 1, wherein a radially outermost region of the inwardly directed bead is collapsed in an axial direction to substantially close the bead to an area surrounding the can body.
 12. A can according to claim 1, wherein the inwardly directed bead has a substantially oval axial cross-sectional shape.
 13. A can according to claim 1, wherein each one of the upwardly facing sealing surface and the inwardly facing surface defined by the bead is substantially convex.
 14. A can according to claim 1, wherein the outwardly facing surface of the lid wall is substantially flat.
 15. A can according to claim 1, wherein the can body and the lid are dimensioned such that, when the lid is press-fitted into the opening of the can body, an upper surface of the lid is below the top of the can body.
 16. A can according to claim 1, wherein when the lid is engaged with the can body, the outwardly facing surface of the lid wall abuts the inwardly facing sealing surface of the bead, thereby providing a metal to metal seal.
 17. A can according to claim 1, wherein, when the lid is engaged with the can body, the sealing compound extends over the outwardly facing surface of the lid wall to seal said outwardly facing surface to the inwardly facing sealing surface of the bead. 